1. Field of the Invention
The invention relates to a method for the orientation of a parallax barrier screen on a display screen.
2. Description of the Background Art
Approaches to the field of parallax barriers have existed for some time. A pioneer in this field was Frederic Ives who in the publication GB 190418672 A proposed a system with a “line screen” for 3-D imaging. Further, fundamental findings on the use of barrier screens for 3-D imaging are described in the publication by Sam H. Kaplan “Theory of parallax barriers,” Journal of SMPTE, Vol. 59, No. 7, pp. 11-21, July 1952.
A widespread dissemination of autostereoscopic systems did not succeed for a long time, however. An actual renaissance of 3-D systems did not occur until the eighties of the 20th century, because of the now available computing power and novel display technologies. In the 1990s, the number of patent applications and publications for glasses-free 3-D visualizations positively shot up. Outstanding results were achieved by the following inventors or suppliers:
In JP 08331605 AA, Masutani Takeshi et al. describe a step barrier in which a transparent barrier element has approximately the dimensions of a color subpixel (R, G, or B). With this technology, it was possible for the first time to transfer the resolution loss occurring in most autostereoscopic systems in the horizontal direction, due to the representation of simultaneous multiple views (at least two, preferably more than two views), in part also to the vertical direction. A disadvantage here, as in all barrier methods, is the high light loss. In addition, the stereo contrast with sideways movement of the viewer changes from almost 100% to about 50% and then increases again to 100%, which as a result has a fluctuating 3-D image quality within the viewing space.
In German Pat. Appl. No. DE 100 03 326 C2, Armin Grasnick et al. achieved a refinement of the barrier technology in regard to two-dimensional structured wavelength-selective filter arrays to produce a 3-D impression. A disadvantage here as well, however, is the greatly reduced brightness of this type of 3-D systems in comparison with a 2-D display.
Finally, Wolfgang Tzschoppe et al. filed the International Pat. Appl. No. WO 2004/077839 A1, which relates to a barrier technology improved in regard to brightness. Based on the approach of a step barrier disclosed in JP 08331605 AA and DE 100 03 326 C2, a special line-to-space ratio of the transparent to the opaque barrier filter elements is presented here, which is greater than 1/n with n being the number of the displayed views. The embodiments and teaching disclosed in this publication, however, usually produce unpleasant moiré effects and/or a greatly limited depth perception, because the stereo contrast is greatly reduced, compared with, for instance, the teaching of JP 08331605 AA.
In U.S. Pat. Appl. No. 2006/0051109 A1 (Lim et al.), the manufacturing of a 3-D screen is described, in which a 3-D imaging device (e.g., a lens or a barrier screen) is aligned before a screen and then in the correct orientation an adhesive bond is hardened. In this regard, a black stripe is characteristically produced, which is observed by an operator or camera. Of particular disadvantage here is that the required correctness is not necessarily achieved during the aligning with use of a black stripe or a black area alone. The additionally proposed method of using at least one left and one right image with different image contents in each case of a completely white and a completely black area as an alignment test pattern, on the contrary, requires the evaluation of two disjunctive partial images, namely, the left and the right.
German Pat. No. DE 102 52 830 B3 (Maly-Motta) describes an autostereoscopic adapter for a flat panel display, which undergoes automatic calibration via an electro-optic sensor. No statements are made about the test patterns employed thereby, however, so that no conclusions can be drawn on the quality of the final calibration.